If they have what I need, then it's easier and quicker for me to work it into my site. If I have to wait for them to create a banner or create it myself, then obviously it'll take longer for me to start promoting them.

But seriously, if I want to promote a site badly enough and I need a 920 x 100 banner, I'll just make my own banners. I prefer to make them anyway because I like the banners to fit into the overall design of my site. I don't like banners with big honking "click here for $1.95 trial" flashing all over the place.

Michael